Tax Re Rental Property

[zingo1327]

I rent out a small flat through a letting agency who charge me a monthly fee. For ease I'll use the sums £500 and £400. (£100 fee)
At present when I fill in my tax return I put down £400 as earnings (ie no costs)
Would it benefit me to put down £500 as earnings and £100 as costs (against tax) or doesn't it matter whichever way I do it?

[Gizmonster]

I don't think it would benefit you financially, but I would put it in as £500 earnings and £100 costs.
You really should put down everything as it is, irrespective of whether it makes a difference to your tax or not.
The reason I say this is I had my tax return queried one year and one of the things I was pulled on was not including interest earned on my savings (this was back in the day when interest on your savings was taxed at source).
I wasn't actually penalised for it, as they were querying other things, but I was given a slap on the wrist and told to make sure I included everything on my tax return (even though it made no difference whatsoever to my tax).